When you spawn a new actor, its variables are reset, so if you want it to have a different value when spawned, you need to save it somewhere that doesn’t get affected by the character spawning, like for instance, the PlayerController. Then, when you spawn the character, you immediately set its health to the value saved in your player controller, or you can simply expose the Character’s health OnSpawn and feed it the desired health from your player controller.
If you’ve got any more questions let me know 